Visualization inside the human body is an indispensable tool to enable the physician to perform an accurate diagnosis of a variety of illnesses, to deliver therapeutic agents and/or to perform minimal invasive surgical operations inside the body. Obviously to reduce trauma for the patient, such procedures are better performed through the natural orifices of the human body, whenever possible, however sometimes it is necessary to use invasive techniques and to penetrate the human body through the skin. A very large number of endoscopic devices exist nowadays. These devices, which consist of an elongated body provided with channels through which medical devices can be inserted, and fluid or air/CO2/vacuum or other devices, for example for ablation, cutting, sealing, approximating tissues, etc., can be delivered or withdrawn, are introduced into the body up to the point where the procedure is to be performed. Obviously such devices can be independently used as stand alone devices and do not necessarily have to be used through channels. Many of these endoscopic devices are provided with a built-in camera, and others have cameras introduced through channels in the body of the endoscopic device. In this context and throughout this specification, the term “endoscopic device”, used in the context of medical applications, refers to any elongated device that can be inserted into human cavities, either through the natural orifices, through an incision in the skin, or first through a natural orifice and then through a incision in an internal organ. A non exclusive list will contain for example, conventional endoscopes such as colonoscopes, bronchoscopes, laparoscopes, ureteroscope, cystoscope, angioscope, durendoscope, but other devices should be also included, for example, needles, catheters, laryngoscopes, staplers, guidewires, papilotomes, cutters, balloons, forceps, trocars, etc.
As said, due to their size all the abovementioned instruments cannot reach certain locations in the body without causing a significant trauma to the patient. Others might severely endanger the safety of the patient and due to their size might cause severe damages. Three illustrative examples are the human brain, the ear canal, and heart arteries. In an endoscopic brain surgery procedure performed through the nose, i.e., trans-nasal, it is not possible to advance one of the prior art instruments due to the dimension involved in creating a tunnel and the brain configuration. Moreover, if an instrument greater than 2 mm is introduced without a good image and superb articulation, safety and trauma issues will block it before it reaches its destination. In the second example, the Eustachian tube has a typical dimension of approximately 1.5 mm (in adults). In order to view the canal a small diameter device with good articulation is needed. The device must negotiate the turns in the anatomical configuration without causing trauma to the patient. The same problem applies to other organs as well, such as heart arteries, kidneys, common bile duct, pancreas, lungs, etc.
As said, while the invention is applicable to uses other than medical, such as veterinary, industrial, research, etc., the description to follow will be made with reference to medical applications in particular, since its relevance to other fields will be readily apparent to the skilled person. For example, industrial applications are inspection of turbine blades, of containers that contain radioactive or biologically hazardous fluids, of the interiors of very narrow pipes, or of the interior of closed containers or chambers that can only be accessed through very small diameter openings.
Cameras used in state-of-the-art endoscopic equipment are typically high-quality CCD cameras, equipped with illumination sources and optical fibers to propagate the light. These cameras require superb electronics and state-of-the-art sensors, optics and image processing, as well as hand assembly of the camera head and optics, all of which results in very expensive equipment. The resulting equipment has to be reused via sterilization because of cost considerations, which in turn entails handing costs.
In order to reduce trauma for the patients, small diameter endoscopic devices are preferred. The envelope of the device (its outer cross-section) will be defined by its internal components. Thus, in order to reduce the overall diameter of the endoscopic device, the internal components must be consequently small. This requirement dictates compromises when designing endoscopic devices, because, for example, large working channels, i.e. the pipes which enable other tools to enter the region of interest in the body through the endoscopic device without affecting the internal parts of the endoscopic device, will dictate the use of a small imager or minute cables for articulation, or minimum illumination, etc.
It is well known in the art that miniature imagers suffer from noisy images due to insufficient illumination caused by small diameter illumination fibers, VCSELs or LEDs employed. In order to overcome some of these problems, a compromise must be made based on the primary goal of the device, i.e., whether a small diameter is more important than a high-quality image, or whether minimum assembly costs must be achieved, etc. All this dictates that in order to produce a good image which is acceptable to the physician in order to be able to perform the required procedure, a quality pixel array should be employed in currently available devices. The sensor must be coupled to state of the art short length optics and provided with white light generated usually by an arc lamp such as Xenon, good illumination fiber that withstands a small diameter bending radius, and the like requirements.
The smallest available imaging sensor, the illumination means (fibers, VCSELs or LED) and the internal maneuvering means (mechanical or electrical), dictate the internal dimension of the endoscopic device. In addition, an external sheath, sometimes used in conjunction with a braid or a metal spring will dictate the external dimension, known as the Outer Diameter of the endoscopic device. Obviously in order to perform an endoscopic procedure through a natural orifice, the Outer Diameter must be small in comparison to the dimensions of the orifice itself. Thus, for example. In Ears-Nose-Throat (ENT) procedures, the dimension of an existing ENT endoscopic device will be in the range of 2-3.6 mm. Taking into account that the smallest CCD available on the market (manufactured by Sony), is in the range of 1.4 mm×1.4 mm—including its package with approximately 120K effective pixels, which of course requires a certain amount of light in order to generated an acceptable raw signal (analog) to be sent to an image processing unit which usually is located externally to the endoscopic device—it is possible to show that the minimum Outer Diameter of an endoscopic device without working channel should be in the range of the sensor's diagonal plus 0.15 mm (for wall thickness of the external sheath), i.e. 2.11 mm. Adding a working channel and another channel for irrigation/insufflations or suction will increase this diameter to a realistic diameter of 3 to 3.6 mm. On the other hand, it is possible to use the smallest available CMOS sensor for imaging purposes, hence utilizing the strength of micro electronics and cheaper production of such wafers. For example, a CMOS sensor with only 10K pixels that measures 1 mm×1 mm including CSP package (manufactured by Cypress), includes all electronics needed to generate an image (digital) to be presented on screen. Such a sensor will yield an endoscopic device with minimum Outer Diameter of 1.6 mm without any working channel but with a poor image in comparison to the CCD image. In fact, this 1 mm×1 mm with 10K pixels CMOS sensor does not provide superior performance than an imaging fiber with the same diameter however with 20K pixels. It is however smaller in diameter than the CCD sensor, and therefore may be used in a procedure where the natural orifice is small and it is possible to compromise regarding the quality of the image. As will be appreciated by the skilled person, producing miniature image sensors presents difficult design and production challenges because the yield is low, the assembly is complex and time consuming, and the sensors are expensive.
In both cases discussed above, it was assumed that the cable that connects the imager to the video processing unit or directly to the monitor is smaller than the imager itself. This however very much depends on the imager's design (analog or digital), the number of pads in the package, and its dimension. In most of the imagers available today the minimum number of pads is 6 to 24 for CMOS and 8 to 14 for CCD. Since current technologies suggest that each pad has a minimum dimension (150 to 350 microns), this affects the overall dimension of the imager, hence the endoscopic device Outer Diameter. These two extreme solutions explain the problem, on the one hand an imager that provides a good image together with some additional pipes (for working channel and/or irrigation/insufflations/suction) and illumination means requires a larger diameter endoscopic sensor and expensive components. Hence the result is an expensive endoscopic tool that must be reused in order to receive a return on investment. On the other hand is the imager that offers low resolution imaging but still results in an expensive tool due to the other components, assembling, and labor that are associated with the production of such devices.
In order to reach an optimized result, both in respect of the trauma to the patient, safe procedure, and the cost of the device—or in other words, the smallest possible Outer Dimension and the smallest incision required to introduce the device into the body, while keeping minimal cost so it can be produced as a mass production article that is disposable—a new set of problems, never before addressed in those terms in the art, must be solved.
It would therefore be desirable to provide a solution that overcomes the disadvantages of the prior art, both in respect of design, construction, functional problems and of costs of a small diameter visualization probe or endoscopic device.
It is an object of the present invention to provide such a solution, which overcomes the disadvantages of the prior art.
It is another object of the invention to provide surgical, therapeutic and/or diagnostic devices equipped with visualization means, which are relatively inexpensive.
Other objects and advantages of the invention will become apparent as the description proceeds.